MCQ Quiz: Exposures in Pharmacoepidemiology

In any pharmacoepidemiologic study, a clear and accurate definition of the “exposure”—typically a medication—is just as critical as the outcome being measured. How researchers ascertain drug exposure from sources like claims data or electronic health records can introduce significant bias and affect a study’s validity. The ability to critically appraise exposure measurement is a key skill taught in the Principles of Evidence-Based Practice course. This quiz will test your knowledge on the concepts, challenges, and biases related to defining and measuring drug exposures in pharmacoepidemiologic research.

1. In a pharmacoepidemiology study investigating the risk of a side effect from a new medication, the “exposure” is:

• a. The side effect being studied.
• b. The new medication.
• c. The study population.
• d. The statistical analysis.

Answer: b. The new medication.

2. In a case-control study, patients with a rare disease (cases) are asked about their medication use from ten years ago, while healthy patients (controls) are asked the same question. If the cases remember their past exposures more accurately than the controls, what type of bias has occurred?

• a. Selection bias
• b. Attrition bias
• c. Recall bias
• d. Publication bias

Answer: c. Recall bias

3. A researcher uses a pharmacy claims database to identify “exposure” to a medication. What is a major limitation of this data source?

• a. It proves the patient was adherent and took the medication as prescribed.
• b. It only shows that a medication was dispensed, not that the patient actually ingested it.
• c. The sample sizes are typically too small.
• d. It contains detailed clinical lab values.

Answer: b. It only shows that a medication was dispensed, not that the patient actually ingested it.

4. The PICO format is used to formulate a clinical question. The “I” can stand for “Intervention” or what other equivalent term?

• a. Indication
• b. Incidence
• c. Exposure
• d. Institution

Answer: c. Exposure

5. “Confounding by indication” is a major challenge in pharmacoepidemiology. It refers to the fact that:

• a. A drug is used for an off-label indication.
• b. The reason a patient is prescribed a drug (their underlying disease) is itself a risk factor for the outcome.
• c. The indication for a drug changes over time.
• d. The drug has no clear indication.

Answer: b. The reason a patient is prescribed a drug (their underlying disease) is itself a risk factor for the outcome.

6. The “Pharmacoepidemiology Study Designs” is a specific learning module in which course?

• a. PHA5244 Principles of Evidence-Based Practice
• b. PHA5104 Sterile Compounding
• c. PHA5703 Pharmacy Law and Ethics
• d. PHA5787C Patient Care 5

Answer: a. PHA5244 Principles of Evidence-Based Practice

7. A study finds that as the dose of a medication increases, the risk of a specific adverse event also increases. This is known as a:

• a. Dose-response relationship.
• b. Selection bias.
• c. Recall bias.
• d. Composite outcome.

Answer: a. Dose-response relationship.

8. Ascertainment of exposure refers to:

• a. Defining the outcome of the study.
• b. The method by which a researcher determines whether a study participant was exposed to the factor of interest.
• c. The statistical analysis of the exposure.
• d. The final conclusion of the study.

Answer: b. The method by which a researcher determines whether a study participant was exposed to the factor of interest.

9. In which study design is recall bias the biggest concern for exposure ascertainment?

• a. Randomized controlled trial
• b. Prospective cohort study
• c. Case-control study
• d. All of the above equally.

Answer: c. Case-control study

10. “Temporality” is a key concept in establishing causality. A prospective cohort study is strong in this regard because:

• a. It looks backward in time.
• b. It measures exposure and outcome at the same time.
• c. It establishes that the exposure occurred before the outcome.
• d. It is free from all confounding.

Answer: c. It establishes that the exposure occurred before the outcome.

11. The appraisal of observational studies is a specific lecture within the Principles of Evidence-Based Practice course.

• a. True
• b. False

Answer: a. True

12. A study defines “exposure” as a patient having at least one dispensed prescription for a statin in the past year. This is an example of a(n):

• a. Vague exposure definition.
• b. Specific and operational exposure definition.
• c. Outcome definition.
• d. Confounder definition.

Answer: b. Specific and operational exposure definition.

13. When an interviewer asks more probing questions about potential side effects to patients they know are taking a new drug compared to those on placebo, this is an example of:

• a. Recall bias
• b. Interviewer bias (a type of information bias)
• c. Selection bias
• d. Attrition bias

Answer: b. Interviewer bias (a type of information bias)

14. A key role of a pharmacist when appraising a pharmacoepidemiology study is to:

• a. Accept the authors’ definition of exposure without question.
• b. Critically evaluate how exposure was defined and measured and assess its potential for bias.
• c. Only read the conclusion of the paper.
• d. Assume all data from EHRs is perfectly accurate.

Answer: b. Critically evaluate how exposure was defined and measured and assess its potential for bias.

15. “Journal Club” is an activity where students practice critically appraising all parts of a study, including the exposure definition.

• a. True
• b. False

Answer: a. True

16. Which of the following is a limitation of using patient self-report to determine drug exposure?

• a. It is subject to recall bias.
• b. Patients may not know the names of all their medications.
• c. Patients may not report socially undesirable medication use (e.g., substance abuse).
• d. All of the above.

Answer: d. All of the above.

17. The “Experimental Studies” module, which describes how exposure is assigned by a researcher, is part of the EBP course.

• a. True
• b. False

Answer: a. True

18. A “time-varying exposure” is one that:

• a. Is only taken at a specific time of day.
• b. Can change over the course of the study period (e.g., a patient starts and stops a medication).
• c. Is only studied for a short time.
• d. Has a short half-life.

Answer: b. Can change over the course of the study period (e.g., a patient starts and stops a medication).

19. Why can confounding by indication lead to a false conclusion that a drug is harmful?

• a. The drug itself is not harmful.
• b. The drug is often given to sicker patients who are already at a higher risk of the adverse outcome, regardless of the drug.
• c. The drug is only given to healthy patients.
• d. The outcome is not measured correctly.

Answer: b. The drug is often given to sicker patients who are already at a higher risk of the adverse outcome, regardless of the drug.

20. An active learning session on EBP is part of which course?

• a. PHA5244 Principles of Evidence-Based Practice
• b. PHA5163L Professional Skills Lab 3
• c. PHA5781 Patient Care I
• d. PHA5787C Patient Care 5

Answer: a. PHA5244 Principles of Evidence-Based Practice

21. Using a prescription dispensing record from a pharmacy database is an objective way to measure drug exposure.

• a. True
• b. False

Answer: a. True

22. An “active comparator” design in a pharmacoepidemiology study helps to reduce confounding by indication because:

• a. It compares users of one active drug to users of another active drug who likely have a similar underlying reason for treatment.
• b. It compares users of a drug to non-users.
• c. It eliminates all bias.
• d. It is a type of randomized trial.

Answer: a. It compares users of one active drug to users of another active drug who likely have a similar underlying reason for treatment.

23. The “Introduction to study designs in pharmacoepidemiology” is a required reading in the EBP course.

• a. True
• b. False

Answer: a. True

24. An active learning session on cohort study appraisal is part of the Patient Care 5 curriculum.

• a. True
• b. False

Answer: a. True

25. A pharmacist documenting a medication in a structured field within an EHR is creating data that is more useful for determining exposure than if they wrote it in a free-text note.

• a. True
• b. False

Answer: a. True

26. Which of the following is the most difficult exposure to accurately ascertain from a claims database?

• a. A dispensed prescription for lisinopril.
• b. A surgical procedure.
• c. The use of an over-the-counter medication like aspirin.
• d. A diagnosis of hypertension.

Answer: c. The use of an over-the-counter medication like aspirin.

27. A study defines exposure as “current use” if a patient had a dispensed prescription in the 30 days prior to the outcome. This is an example of:

• a. A case-control design.
• b. An operational definition of exposure.
• c. A primary outcome.
• d. A confounding variable.

Answer: b. An operational definition of exposure.

28. An active learning session on study design is part of which course module?

• a. Module 2: Pharmacoepidemiology Study Designs
• b. Module 1: Formulating a Clinical Question
• c. Module 6: Summarizing the Evidence
• d. Module 3: Applying Biostatistics

Answer: a. Module 2: Pharmacoepidemiology Study Designs

29. The term “immortal time bias” can occur in a cohort study when:

• a. The study lasts for a very long time.
• b. There is a period of follow-up time where a patient cannot experience the outcome but is incorrectly included in the analysis.
• c. All participants in the study are elderly.
• d. The outcome being studied is death.

Answer: b. There is a period of follow-up time where a patient cannot experience the outcome but is incorrectly included in the analysis.

30. The EBP course covers different types of study designs.

• a. True
• b. False

Answer: a. True

31. In a study of a vaccine’s safety, the “exposure” would be:

• a. The disease being prevented.
• b. The receipt of the vaccine.
• c. The age of the participant.
• d. An adverse event.

Answer: b. The receipt of the vaccine.

32. A major advantage of using EHR data to ascertain exposure is the potential to access:

• a. The prescribed dose and directions.
• b. The patient’s adherence data.
• c. The patient’s genetic information.
• d. The cost of the medication.

Answer: a. The prescribed dose and directions.

33. Misclassification of exposure status (i.e., classifying an exposed person as unexposed) can lead to what type of bias?

• a. Selection bias
• b. Information bias
• c. Attrition bias
• d. Publication bias

Answer: b. Information bias

34. A pharmacist must be able to evaluate how well an exposure was measured to determine a study’s:

• a. External validity
• b. Statistical power
• c. Internal validity
• d. Cost-effectiveness

Answer: c. Internal validity

35. A researcher wants to study the effect of a PRN (as-needed) pain medication. What is a major challenge in defining the exposure?

• a. It is difficult to determine the exact quantity and frequency of use from dispensing records alone.
• b. The medication has no side effects.
• c. All patients take it every day.
• d. It is not a real medication.

Answer: a. It is difficult to determine the exact quantity and frequency of use from dispensing records alone.

36. A study comparing a new drug to a placebo has a clear definition of exposure.

• a. True
• b. False

Answer: a. True

37. Which of the following is the LEAST objective measure of exposure?

• a. Pharmacy dispensing records.
• b. EHR prescription orders.
• c. Patient self-report from 5 years ago.
• d. A biomarker indicating drug presence.

Answer: c. Patient self-report from 5 years ago.

38. The “P” in the PICO question (Patient, Intervention, Comparison, Outcome) can be thought of as defining the study population and the “I” defines the ______.

• a. outcome
• b. exposure
• c. confounder
• d. bias

Answer: b. exposure

39. A pharmacist reading a study should always ask:

• a. “How was drug exposure defined and measured?”
• b. “What were the potential sources of error in measuring the exposure?”
• c. “Could misclassification of exposure have biased the results?”
• d. All of the above.

Answer: d. All of the above.

40. An active learning session covering EBP is part of which course?

• a. PHA5244 Principles of Evidence-Based Practice
• b. PHA5163L Professional Skills Lab 3
• c. PHA5781 Patient Care I
• d. PHA5787C Patient Care 5

Answer: a. PHA5244 Principles of Evidence-Based Practice

41. The strength of a pharmacoepidemiology study relies heavily on the quality of its exposure and outcome data.

• a. True
• b. False

Answer: a. True

42. Which of the following exposures would be easiest to accurately identify using a claims database?

• a. Use of aspirin
• b. Use of a specific, prescription-only statin
• c. Use of an herbal supplement
• d. A diet high in fat

Answer: b. Use of a specific, prescription-only statin

43. A study’s definition of “exposed” is “ever having received a prescription for Drug X”. A limitation of this definition is that it does not account for:

• a. Dose
• b. Duration
• c. Adherence
• d. All of the above

Answer: d. All of the above

44. A well-designed study will use the same method to ascertain exposure for all study participants.

• a. True
• b. False

Answer: a. True

45. Why can it be difficult to determine the timing of exposure relative to the outcome in a case-control study?

• a. Because the study looks forward in time.
• b. Because exposure information is collected retrospectively, after the outcome has already occurred.
• c. Because the exposure is randomized.
• d. It is not difficult.

Answer: b. Because exposure information is collected retrospectively, after the outcome has already occurred.

46. A “new user” design in a cohort study is often preferred because:

• a. It helps to avoid including patients who have been on the drug for a long time and may be different from new users.
• b. It reduces the sample size.
• c. It is easier to analyze.
• d. It eliminates confounding.

Answer: a. It helps to avoid including patients who have been on the drug for a long time and may be different from new users.

47. A journal club presentation on a pharmacoepidemiology study should include a critique of the exposure definition.

• a. True
• b. False

Answer: a. True

48. An active learning session on pharmacoepidemiology is part of which course module?

• a. Module 2: Pharmacoepidemiology Study Designs
• b. Module 1: Formulating a Clinical Question
• c. Module 6: Summarizing the Evidence
• d. Module 3: Applying Biostatistics

Answer: a. Module 2: Pharmacoepidemiology Study Designs

49. The overall goal when assessing the “exposure” in a pharmacoepidemiology study is to:

• a. Find a reason to discredit the study.
• b. Understand how accurately the study measured what it claims to have measured.
• c. Determine the cost of the exposure.
• d. Assume the measurement was perfect.

Answer: b. Understand how accurately the study measured what it claims to have measured.

50. The ultimate reason for a pharmacist to learn about defining exposures is to:

• a. Be able to critically appraise the validity of a study before applying its results to patient care.
• b. Pass the EBP final exam.
• c. Conduct their own research.
• d. Memorize different types of bias.

Answer: a. Be able to critically appraise the validity of a study before applying its results to patient care.